"It would be better to do nothing than to accept Google's proposals," said Thomas Vinje of FairSearch, a group of 17 companies including Microsoft and TripAdvisor. "The proposals would make things worse rather than better," he insisted.

The European Commission, the bloc's antitrust authority, has been investigating since 2010 whether Google is abusing its dominant market position and stifling competition. It pointed out several areas of concern, which Google is trying to address mainly by changing the way it displays search results.

Google Inc.'s search engine enjoys a near-monopoly in Europe with a market share of about 90 percent, which gives it a huge edge over competitors to promote its own services such as Google News, Google Maps or its shopping and flight search functions.

Complainants in the case had two months ending this week to provide the EU with feedback to the proposed remedies. The body's antitrust chief, Commissioner Joaquin Almunia, already hinted after the first month of the so-called market test that Google would be asked to do more to appease the competition concerns.

Google has offered to more clearly label search results stemming from its own services to allow users to distinguish between natural search results and those promoted by Google. It also agreed to display some search results from its competitors and links to their services.

But competitors say the two months have shown that the way Google would label and display its own offerings to distinguish it from rivals' content actually favors Google.

"This will be a counterproductive measure, it will institutionalize the search bias," said Moritz von Merveldt, head of antitrust matters at German media company ProSiebenSat.1 Group. "Users often will be directed away from competitors' offers," he added.

Merveldt said that a test of Google's new labeling on weather searches showed that his company's weather service would immediately lose 20 percent of its web traffic, and thus make less money from online advertising.

Other industry officials voiced similar concerns.

"As a minimum requirement, Google must hold all services, including its own, to exactly the same standards, using exactly the same crawling, indexing, ranking, display and penalty algorithms," said Helmut Heinen, the president of the federation of German newspaper publishers BDZV.

It might take several months before the EU Commission announces its decision on the case. So far, it has often taken a harder line with U.S. tech companies than its American counterparts, the Federal Trade Commission and the Justice Department.

Google, which is based in Mountain View, California, was able to settle a similar antitrust complaint on its search business with the FTC in January without making any major concessions on how it runs its search engine.

A Google Europe spokesman would not directly comment on the competitors' allegations, referring instead to a statement the company posted on its blog Monday.

"Our proposals are meaningful and comprehensive, providing additional choice and information while also leaving room for future innovation," wrote Google executive Kent Walker. "We think we did a pretty good job."